1. Field of the Invention
The invention relates to a power conversion technique, and more particularly, to a flyback-based power conversion apparatus.
2. Description of Related Art
The primary purpose of applying a power conversion apparatus is to convert an unstable and high alternating current (AC) input voltage supplied by the power company to a stable and low direct current (DC) output voltage suitable for various electronic devices. Therefore, the power conversion apparatus is widely used in computers, office automatic facilities, industrial control equipments, communication apparatuses and so on.
Pulse width modulation (PWM) control chip is applied in most of the control structures of recent power conversion apparatuses. To protect the power conversion apparatus from being damaged because of over temperature (OT), over voltage (OV) and over current (OC), the pulse width modulation (PWM) control chip usually has a plurality of isolated detection pins for respectively executing the detections of over temperature protection (OTP) and over voltage protection (OVP). In other words, each of the detection pins is only corresponding to one type of function detections. Therefore, applying various function detections by the pulse width modulation (PWM) control chip also means to increase the production cost of manufacturing the pulse width modulation (PWM) control chip.